Public and private schools as of May 2011 will be banned from using traditional pesticides. Daycare centers will be banned from using them as of this November.

Some schools, such as the Bayport-Bluepoint School District, have started to replace pesticides with more environmental means of maintaining fields.

“This law will result in a sharp reduction in children’s exposure to pesticides that were applied on school grounds,” Foley said. “Keeping pesticides away from our children will protect them from the harmful side effects that could result.”

Englebright said the state took the action out of a concern that children with developing immune systems can be harmed by continued exposure to pesticides.

Department of Environmental Conservation Commissioner Pete Grannis said the measure makes sense “precisely because infants and children are so much more susceptible to the effects of toxic pesticides than adults.”

Although there’s no clear evidence that pesticides at schools have caused injuries, others said there’s enough reason for concern to prompt action.

“We’ll never have 100 percent evidence that a particular chemical exposure has caused a toxic injury,” said Leo Trasande, a pediatrician and co-director of the Children’s Environmental Health Center at Mount Sinai School of Medicine, in a written statement. “But we have a responsibility to our children to prevent toxic exposures so that they don’t carry the burden of disease in the future.”

While bans on traditional pesticides might seem to lead to more costs, supporters of the law such as Port Washington-based Grassroots Environmental Education said that won’t be the case. The group produced a report showing natural turf management could cost significantly less than traditional lawn treatment.

“Organic lawn care has been proven effective and it’s cost effective,” said Maureen Murphy, executive programs manager for the Citizens Campaign for the Environment. “It should be a cost savings for schools.”

Foley spokeswoman Krystyna Baumgartner said “pesticide-free turf management methods are just as effective in maintaining fields.”

Since pesticides may work best in treating certain lawn problems, hardship provisions would allow them in cases when there’s no effective alternative. “We anticipate it’s few and far between,” Baumgartner said. “It’s only in extreme cases.”

The new law may hurt pesticide makers, but is likely to benefit firms making greener alternatives not banned by the law.

“If the school districts are not going to purchase it, they’ll lose money,” Baumgartner said of pesticide makers. “Companies offering green alternatives would benefit.”

Adrienne Esposito, executive director of Citizens Campaign for the Environment, said schools should save by shifting to green programs without pesticides.

“One school supply that schools will need less of will be toxic pesticides for playing fields, since next year they’ll be prohibited,” she said.